Valve-operating means



Oct. 11, 1927.

,c. R. SHORT VALVE OPERATING MEANS Filed Feb. 18, 1925 Patented Get. 11, 1927.

' UNITE CHARLES R. SHORT, 0F DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS RESEARCH CORPORATIOhL-OF DAYTON, OHIO, A CORPORATION" OF DELAWARE.

VALVE-OPERATING MEANS.

Application filed February This invention relates to improvementsin means for operating poppet valves Of ID- ternal-combustion engines, and'more particularly to such means wherein the valve is opened by the pressure of one end of a rocker arm on the valve stem, and is closed by a spring.

The object'of the invention is to avoid lateral pressure by the rocker arm on the valve stem, due to its angular movement, which tends to skew or cramp the stem 1n its slide bearing.

The invention consists in the combination of a poppet valve and stem, with a rocker arm that has a curved bearing surface intersected by the axis of the valve stem, and

transmits its pressure to the valve stem along lines parallel with the axis of and lylng within said stem. It further comprises a roller interposed between the end of the valve stem and the work-end of the rocker arm, and a suitablemeans for holding the roller to the rocker arm in such manner that it may be free to roll on bearing surfaces on the rocker arm and valve stem during the angular movements of the work-end of the arm. The invention also consists .in subcombinations and details. of structure described in the specification, illustrated in the drawings, and defined in the appended claims.

In the drawings, inwhich like reference characters indicate like parts throughout the several views;

Fig. 1 1s a fragmentary section crosswlse .of an engine block and parallel with the direction of piston movement, showing in side elevation a valve-operating rocker arm and so much of a valve stem as is necessary to illustrate the invention;

Fig. 2 is a plan view of the rocker arm I detached from the engine, but showing the roller and means for holding it to the workend of the rocker ,arm;

Fig. 3 is a perspective view of a roller and a spring used to hold the roller t0 the rocker arm in such manner that the roller may be free to roll during the angular movements of the arm;

Fig. 4 shows in side elevation, much enlarged, the work-end of the rocker arm with roller and spring in place.

One of the difliculties recognized in operating poppet valves through the intermediary of a rocker arm or rocking lever, is

18, 1925. Serial No. 10,142.

that the end of the rocker arm or lever that opens the valve, as commonly designed, applies side pressure upon the valve stem which increase the friction ofthe stem in its slide bearing, causing excessive wear and interference with the freedom of operation of the valve. .This'is because the pressure of the rocker arm is applied obliquely to the valve stem during the larger part of its angular" movement. In constructions embodying this invention, one form of which isillustrated in the drawings, there is substantially no side thrust exerted by the rocker arm upon the valve stem, as the pressure of the arm is exerted always in a direction parallel with the axis of the valve stem.

In the drawings, 10 represents a rocker" arm, 11 a rocker arm shaft, 12 the push rod by which the rocker arm is operated in the usual manner, 13 the valve stem, 14 the slide iearing for the valve stem and 15 a coil spring tending always to close the valve.

The upper end 16 of the valve stem 13 is preferably so formed as to afford a good bearing surface for a roller. The operative surface 17 of the work-end of the rocker arm is disposed so that the axis of the valve stemv contact of the roller upon the surface 17 through the axis of the roller 18 will remain parallel with the axis of the valve stem.

The roller 18'may be held against the bearing surface 17 by means of a spring 19 so connected to the rocker arm and to the roller as not to interfere with free rolling movement of the roller as necessitated by the angular or arcuate movement of the workend of the rocker arm. A preferred form of construction of a spring for this purpose is indicated in Fig. 3. It consists of spring wire, formed as shown, into two parallel U- shaped members or limbs 20, as viewed from the side of the rocker arm, one limb of each U-shaped member being connected to the .a line extendin other limbs of each U-shaped member there extend toward each other in alignment and parallel with member 21, two gudgeons 22, which enter a bore or aligned sockets 23 in the roller 18. abl greater diameter than. that of the gud geons 22. As shown in the drawings, the bore 23 may beof a diameter about four times that of the gudgeons on the spring. When the spring and roller are assembled with the rocker arm, the cross member 21 of the spring is engaged in the notch 24 on the back of the rocker arm 10, the U-shaped limbs 20 extending toward the shaft 11, axis of the gudgeons 22 being, when the rocker arm is substantially in mid-throw, approxlmalely intersected by the axis of the valve stem.

Although the spring 19 is shown as of U-shape in side elevation, it will be evident that this is only one form of many that nnght be used that would function in the same manner, and that other forms'of connection between the spring limbs and the roller might be used that would allow free rolnng action of the roller. It will also be evident that the objects of the invention may be achieved to a degree where other forms of bearing elements than rollers are used at the end of the valve stem.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a valve-operating mechanism, the combination of a spring-retracted poppet valve having a stem, with a rocker arm, a roller revolvably mounted in a floating frame and interposed between the rocker arm and the valve stem so as to have a rolling engagement between said valve stem and said rocker arm throughout the angular movements of the rocker arm.

2. Mechanism such as defined in claim 1, in which the rocker arm is formed with a roller bearin surface of such contour that in all operative positions of the rocker arm from a point of contact between the rol er bearing surface on the rocker arm through and perpendicular to the axis of the roller will be parallel to the axis of the valve stem.

3. Mechanism such as defined in claim 1, in which the roller is retained in contact with the bearing surface of the rocker arm The bore 23 is of consider-' by means of a spring which comprises the said frame.

4. Mechanism such as defined in claim 1, in which the roller is provided with a coaxial bore and a spring element constituting a roller frame has a gudgeon of smaller diameter than the bore engaging in said bore to retain the roller against the bearing surface of said arm.

5. Mechanism such as definedin claim 1, I

in which a spring having recurved limbs is attached to the rocker arm and the free ends of the limbs, engage the roller in operative position.

6. Mechanism such as defined in claim 1, in which the rocker arm has a transverse seat opposite the bearing surface and a spring retains. said roller in operative position, said spring comprising two recurved limbs the stem, and a floating cylindrical roller re-- volvably mounted in a spring frame suspended from the end of the rocker arm for establishing a minimum rolling contact.

9. A valve operating mechanism including a spring frame removably attached' to one end of a rocker arm formed with a curved bearing surface, said frame revolvably carrying a cylindrical roller arranged to make a yielding rolling contact with a rod of the valve operating mechanism and the saidbearing surface in such manner that a plane tangent to the bearing surface of the rocker arm at a point of contact with said roller will be perpendicular to a line parallel with the axis of the said mechanism and within the same.

10. A means for taking up lash in a valve operating mechanism and to prevent lateral wear in a valve stem including a spring frame removably mounted on the outer end of a rocker shaft and having a floating bifurcated part which rotatably carries a cylindrical roller.

In testimony whereof I hereto aflix my signature.

' CHARLES R. SHORT. 

